1990 Volvo 760 Volvo intermitant stalling

Problem is back again. 1990 760t 100,000 miles in great shape but is still stalling out whenever it fells like it. Hasnt stalled for about a month but today it stalled out twice at hiway speeds, pulled over and tried to restart, it did not go after first 5 second attempt but started on the second try, I recently replaced the timing pick-up and swapped the suppressen and fan relay with each other, the fuel pump relay appears to be in good condition, so what should I try, keep putting new parts on or get a new car? It never stays dead long enough to test anything. Getting fed up!